1. Field of Invention
The present invention involves boiler flue gas dust removal technology, and an energy-saving electrostatic dust collector is put forward to increase the dust removal rate by lowering flue gas temperature.
2. Description of Related Arts
Flue gases discharged from a boiler contain SO3 due to that coals burned in the boiler contain an S element. The SO3 not only can form acid rain that pollutes the environment, but also can be condensed, together with water vapor in the flue gases, into a dew formation to corrode a device when the flue gas temperature is too low. Therefore, the flue gas temperature of a power plant boiler or of an industrial boiler is generally between 140° C. and 160° C. or even higher. The flue gas temperature has a relatively great impact on operating performance of an electrostatic dust collector. In one aspect, a volume of the flue gases increases with the increase of the flue gas temperature, and therefore a wind speed of an electric field also increases, thereby lowering dust collection efficiency. In another aspect, the increase of the flue gas temperature may lower a spark voltage, which is unfavorable for the dust collection. Apart from this, the level of the flue gas temperature also affects a fly ash resistivity directly. When the flue gas temperature is lowered, the fly ash resistivity decreases, and the dust collection efficiency is improved.
For a cloth bag dust collector, a material of a cloth bag filter is selected mainly according to a range of the flue gas temperature. Therefore, the flue gas temperature must be controlled strictly during use. The flue gas temperature is lowered into a temperature range that can be tolerated by the cloth bag filter for long-term operations. In a general heat exchange device, acid dew corrosion is incurred by direct heat exchange between flue gases and a working medium to be heated. Therefore, after being used, the device will definitely be corroded while the flue gas temperature at an inlet of the electrostatic dust collector is lowered. Thus, such an apparatus which not only can lower a flue gas temperature but also can avoid occurrence of acid dew is needed.